Continuous method of forming and porcelain enameling sheet metal



CALTON .Aug. 30, 1949.

R. G. v TINUOUS METHOD OF FORMING -AND CELAIN ENAMELING SHEET METAL 5 Sheets-Sheet l CON FOR

Filed Dec. 8, 1944 INVENTOR. I? 6. 91. To.

R. G. CALTON CONTINUOUS METHOD OF FORMING AND PORCELAIN ENAMELING SHEET METAL Filed Dec. 8, 1944 5 Sheets-Sheet 2 m m m m H? G (/11. TON.

IJTTORNEK Aug. 30, 1949. R. G. C ALTON 2,480,711

CONTINUOUS METHOD OF FORMING AND PORCELAIN ENAMELING SHEET METAL Filed Dec. 8, 1944 3 Sheets-Sheet 3 mvm'ron. R 6. (01. Tom. BY

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Patented Aug. 30, 1949 CONTINUOUS METHOD OF FORMING AND PORCELAIN ENAMELING SHEET Robert G. Calton, Nashville, Tenn.

Application December 8, 1944, Serial No. 567,264

2 Claims. (Cl. 29-148) This invention relates to deforming and coating sheet metal and has more particular reference to a continuous method of deforming thin strip sheet metal and porcelain enameling the deformed strip.

One object of the invention is to provide a novel and improved method of continuously deforming and porcelain enameling thin sheet metal.

Another object of the invention is to provide a novel method, as above characterized, wherein a strip of thin sheet metal is continuously fed through a succession of treating zones in which it is deformed to the desired configuration or cross section, coated with frit paste, and fired while it is maintained under sufiicient tension to maintain its shape and to prevent buckling.

A further object of the invention is to provide a novel method, as above characterized, including the step of cooling the moving strip after it has been fired and while it is still under tension.

Other aims, objects and advantages of the inyention will appear in the specification when considered in connection with the accompanying drawings, illustrating selected embodiments of the invention, and, wherein:

Fig. 1 is a diagrammatic elevational view of a single-pass apparatus, with parts broken away to show the interior of certain of the elements;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a diagrammatic elevation showing a double-pass modification;

Fig. 4 is a detail view of one of the rollers of the apparatus of Fig. 3, showing, in section, a piece of concave-convex strip; and

Fig. 5 is a diagrammatic elevational view of a triple-pass modification.

The invention is related to the subject matter of my co-pending application, Serial No. 545,467, filed July 18, 1944, now Patent No. 2,428,307, entitled Methods of and apparatus for porcelain enameling sheet metal.- Its objects, as hereinbefore set forth, relate to the field of porcelain enameled thin sheet metal ranging from 20 to 40 gauge. The present invention, insofaras concerns the application of the vitreous enamel or frit'paste to the sheet, the firing of the coated sheet, and the subsequent cooling thereof, is similar to the invention claimed in my co-pending application. Here, however, the similarity ceases,

and many improvements and advantageous features are incorporated in the invention of the present application.

Referring particularly to Fig. 1- of the drawings; there is shown a single enameling or treating unit, generally designated by the numeral I,

having an upper spray chamber or zone 2 including nozzles 3 for directing a spray of the paste on both sides of the advancing sheet or strip 4. Obviously, the paste may be applied uniformly by other known methods. An intermediate firing chamber or zone 5 contains heating elements 6, specifically shown as electric resistance heating elements. Itwill .be understood, of course, that other suitable heating means may be employed. A lower cooling chamber or zone I is provided including a cooling coil 8 through which is circulated an appropriate cooling medium. The enameling unit is preferably rectangular in horizontal cross section to accommodate the strip 4.

An upper sealing device is mounted on top of the unit I, and includes a pair of horizontal rollers 9, swingably carried by arms l0 pivoted at all on suitable pins or bolts. The rollers 9 swing in,- wardly by gravity to contact opposite faces of the sheet 4. Floating upon the rollers 9, is a hood l2 laterally co-extensive with the strip '4 and having end walls l3. The bottoms of the depending side and end walls of the hood 12 are embraced in a vertical channel l4, suitably formed by angle members l5 secured to the top'of the unit, whereby to form a sliding, substantially gas-tight joint to prevent excessive heat losses. The hood l2 has a slot through which the strip 4 passes and rides on the top of the rollers 9 which rub against it as they rotate in contact with the moving strip.

A somewhat similar lower sealing device is positioned at the bottom of the enameling unit. It is provided with rollers i6 mounted on arms I! pivoted at iii. A hood I9 is floatingly suspended on top of the rollers l6 and makes a sliding joint at 20 with the bottom of unit I. The only essential difference between the lower sealing device and the upper sealing device is that, in the former, the rollers are pivoted outside of the hood; whereas, in the latter, they are pivoted inside of the hood. It will be seen that the sealing device, just described, provides an almost perfect seal between the inside and outside of the unit I through which the strip material may pass freely.

, A coil 2| of light gauge stock, properly prepared to receive the enamel coating, is shown being rotatably mounted on a reel. The stock is withdrawn from the coil by feeder rolls 22, driven by a variable speed motor 23 through a suitable speed reducer 245. However, it is contemplated that any ordinary variable speed drive may be employed. The feeder rolls are provided with suitable surfaces for gripping the stock securely. The strip I is led from the feeder rolls through a tensioning device including idler rolls 25 and 25 and an intermediate tensioning idler 21 carried by an arm 28 pivotally mounted at 29. The tensioning idler is sufficiently heavy and so positioned in operation as to apply enough tensioning force on the strip 4 to keep it taut.

From the tensioning device, the strip is moved through a deforming zone and is shown as being led through a pair of corrugating or crimping rolls 32, shown in plan view in Fig. 2, between which the strip is pressed into corrugated form, in which form it is passed through the unit i. It will be understood that the sealing device and slots of the enameling unit through which the corrugated strip passes may be, and preferably are, shaped to the required corrugated contour. After passing through the enameling unit, the strip 4 emerges and is led through corrugated pull-out rollers 3|, similar to the feeder rolls 22, and drive by a variable speed motor 32 through another gear reducer 33.

The feeder rolls and pull-out rolls are independently driven and the speed of each set is independently varied in operation to maintain the tensioning idler 21 at the optimum position to impart the desired tension to the strip of thin sheet metal being processed.

The operation of the apparatus shown in Fig. 1 is believed to be apparent from the foregoing detailed description of its component parts.

The apparatus of Fig. 3 has many features in common with the apparatus of Figs. 1 and 2. Essentially, however, it provides means for apply-, ing a double coating of vitreous enamel to thin metal strip stock and means for producing a finished product which, instead of being corrugated or crimped, is shown as being concave-convex in transverse section. Of course, the sheet may be flat or embossed, depending upon the requirements. The stock is unrolled from the coil 34 and fed to the apparatus by feeder rolls 35 driven by a variable speed motor 36 through gear reducer 31. The strip 38 is led around idler roll 39 and through enameling unit 40, otherwise similar to the previously described enameling unit I, except that the spray chamber 4| is at the bottom and the cooling chamber 42 is at the top.

Upon emerging from the unit 40 the coated strip is passed through a tensioning device, similar to the tensioning device of Fig. 1, comprising rollers 43 and 44, together with an intermediate tensioning idler 45 mounted on arm 46 pivoted at 41. In this example, as in the one previously described, the tensioning device is constructed and arranged to apply suitable tension to keep the strip taut. In case the sheets are required to be flat, the tension may be increased to stretch the sheet into a flat condition. The roller 44 is shown in side view in Fig. 4 and has a slightly crowned peripheral surface 48 for imparting to the strip a concave-convex section. Preferably, the crowning of the roller 45 is relatively slight, of the order of one-eighth to three-quarters of an inch in a roll twenty-four inches long.

From crowning roller 44 the strip 38 advances to and passes through a second enameling unit 49 in which the spray chamber 50, the firing chamber and the cooling chamber 52 are arranged in that order from top to bottom.

After it emerges from unit 49, the strip is passed around a second crowning roller 53, similar to the roller 44, and thence to pull-out rolls 54, driven by variable speed motor 55 and gear reducer 5E. The finished material from the pull-out rolls 54 may be coiled or cut in lengths as desired.

The combined action of the crowned rollers 44 and 53 and the intermediate firing chamber 5| results in deforming the strip under tension to the aforementioned concave-convex section.

The modification shown in Fig. 5 is constructed and arranged to produce a finished product simi lar to the product of the apparatus of Figs. 3 and 4, that is, a product having concave-convex cross section; although the strip may be fiat or embossed, as desired. In this modification, three enameling units are provided for applying three coats of enamel to the thin strip stock. The strip 51 passes downwardly through the first and last enameling units 58 and 59, hence the order of the chambers therein is the same as in the unit of Fig. 1. Since the strip 51 passes upwardly through intermediate unit 65, the order of the chambers is reversed.

Between the feeder rolls SI and pull-out rolls 62, each being independently and variably driven, as hereinbefore described, are provided two tensioning devices. A first tensioning device, including idlers 63 and 64 and tensioning idler 65, is positioned intermediate the feeder rolls 6! and the first enameling unit 58. A second tensioning device, comprising idlers 66 and 61 together with tensioning idler 68, is positioned between the second and third enameling units. ,The idler 61 is shown as being crowned similarly to roller 44 of Fig. 2, and idler 69, beneathenameling unit 59, also is crowned. By virtue of the rollers, the hereinbefore described concave-convex section is imparted to the strip. The pull-out rolls 62 are preferably fiat, but may be shaped to conform to the concave-convex section of the strip 51,

The three modifications of the invention, hereinbefore described, may be used to apply one, two or three coats of porcelain enamel to very thin sheet metal. Where a plurality of coats is applied, the last coat can be applied with known roller screens to achieve various decorative effects. Moreover, the furnaces may be either vertical, as shown, or horizontal, if the proper tension is applied to the strips.

The corrugated strip leaving the pull-out rolls of the apparatus of Fig. 1, cannot be coiled, but must be cut into desired lengths for convenient handling and shipping. The finished, concaveconvex strips or fiat strips coming out of the apparatus of Figs. 3 and 5 may be formed into a coil having a fairly large diameter without cracking the enamel coat, but preferably also is out into suitable lengths.

An exemplary cross sectional view of a corrugated strip in accordance with the invention appears in Fig. 2. Such strip can be used to advantage for roofing or siding instead of the galvanized iron corrugated strips now on the market. A strip having very fine corrugations or embossed effects may be used for interior or exterior wall coverings.

A cross sectional view of a concave-convex strip in accordance with the invention is shown in Fig. 4 at 38. Panels of material of this type, when fastened to flat walls by means of moulding strips near the edges of the panels, may be drawn in to fit snugly against the surface of a wall. It will be understood that the convex side of the panel faces the wall, and that, after the edges have been drawn in, the panel presents a substantially flat exterior surface. Due to the natural springiness of the metal, such a panel does not tend to bulge out in the center.

According to the invention, various colors of vitreous enamel may be applied, and numerous types of finishes may be obtained by the use of suitable embossing rolls. The sheets, in light weight metal, can be used for installation in interior and exterior wall panels, replacing linoleum and ceramic tile, the cost oi material and installation being considerably less than for conventional panels.

Obviously, the invention is not restricted to the particular embodiments thereof herein shown and described.

What is claimed is:

1. That method of deforming andporcelain enameling thin sheet metal which is characterized by continuously feeding a flat strip of the sheet metal through a succession of treating zones, deforming the moving strip to a pre-determined cross section in the first zone, applying frit paste in thesecond zone, firing the strip in the third zone, and maintaining the deformed strip under suflicient tension to retain its shape and to prevent warping due to the firing temperature during its passage through the second and third zones.

2. The method as set forth in claim 1, wherein the moving strip is passed through a fourth zone in which it is cooled and wherein the strip is maintained under tension during its passage therethrough.

ROBERT G. CALTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

